When flying in an aircraft, whether commercial or military, an emergency exit is a crucial feature that the plane should possess. Thus, for safe travels in the present, most commercial planes like the Boeing 737 and the Airbus A320 include multiple exits in addition to the traditional emergency exit. One such emergency exit is the overwing exit, that of which can be found near a trailing edge of an aircraft wing, allowing passengers to leave the plane in case of emergency. The trailing edge is the rear edge of an aircraft's wings where passengers can utilize an overwing exit if present, hence its name. The overwing exit is a self-help exit and can be operated by passengers in the case of an immediate evacuation using slides from the extended flaps or through an evacuation slide that deploys when the door is opened. Aircraft have 90-second evacuation rules, which sometimes is not possible with the main doors, and using a traditional emergency door is not required; in such cases, overwing exits come into play. They are typically smaller than traditional standard emergency exits due to their smaller width and height, and the passenger seated next to the overwing exit is responsible for opening the exit gates.
Unnecessary use of overwing exits can be disastrous for passengers if they do not follow the guidelines given to them during boarding. In certain cases, frequent fliers may attempt to initiate the opening process for emergency exits for evacuation without having proper knowledge or first getting confirmation from the pilot to evacuate the plane. This can lead to danger when exiting too early in these circumstances, so it is suggested that one not touch the emergency exits unless and until commanded. Another risk associated with overwing exits is the escape not being appropriately opened, resulting in damage. This generally happens when the passenger sitting next to the emergency door does not pay attention to the given briefing during boarding or does not follow proper instructions.
The Function of Overwing Exits
In modern aircraft, two types of overwing exits are used, those of which are also called disposable hatch-type exits. These two types are type IIIA and type IIIB exits, where the type IIIA is the oldest and the most common type of overwing exit used in aircraft such as the Airbus A320. In this type, a plug or hatch needs to be removed from its frame in order to open the exit. In type IIIB exit, the user does not have to remove any plug, and it is a self-disposing exit generally found in recent aircraft designs, such as the next generation Boeing 737. The type IIIB exit is designed to ease the opening and minimize the hazards. This can be done by pulling the handle on the door in and down, the handle on the door and triggering the exit self-opening mechanism.
Moreover, the over-wing exit may have an automatically inflating slide attached to the fuselage that is equal to the height of an aircraft measured from the ground. Once the exit is opened, the slide is deployed automatically and inflates, providing a way to evacuate from the wing to the ground. When deployed, the emergency lighting of the aircraft will work only in the direction of evacuation. If there are two pairs of over-wing exits available on the plane, such as on the Boeing 767-300 with a total of four over-wing exits, opening one of the pair of doors will deploy the slide. When the automatic inflation fails, there is also a manual inflation handle available at the door of each exit which can be pulled to inflate the slide.
Difference Between Overwing and Traditional Exits
Almost every commercial aircraft has a traditional emergency exit door and an over-wing exit. Though both are used as an escape route during an emergency for passengers, they have several differences. The first difference is the placement of the emergency exit, where an overwing exit is normally placed near the trailing edge of the aircraft wing. Meanwhile, the traditional emergency door is available in other places. Moreover, the size of the overwing exit is much smaller and narrower than the traditional emergency door, and the overwing exit has less capacity to evacuate passengers during an emergency compared to the emergency exit door.
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